Circumbilical retractor muscle attachment areas have been found in Tropidodiscus pusillus (Barrande in Perner, 1903) from the Middle Ordovician (Darriwilian) of the Barrandian Area, Bohemia. The location and shape of the attachment areas confirm that Tropidodiscus belongs to bellerophontoidean gastropods. In spite of the fact that the species is very abundant, covering bedding planes and filling concretions in countless masses, only two specimens have been collected showing the muscle scars. This is due both to the small dimensions of the shell and to rather disadvantageous preservation of strongly contracted internal moulds. Tropidodiscus pusillus is interpreted as a suprabenthic to epinektic genus living on algal thalli, characteristic for the Tropidodiscus Community (Horný 1997d).